Image editing method and image editing apparatus

ABSTRACT

An image editing method comprises storing original images, storing alpha masks corresponding to the original images, respectively, superposing in turn object images that are extracted from the original images by the alpha masks, to display a composite image on a first display region of a display screen, modifying selectively the alpha masks on a second display region of the display screen to modify the composite image as necessary, and displaying the composite image reflecting modification of at least one of the alpha masks on the second display region.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. 2002-197228, filed Jul.5, 2002, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an image editing method and animage editing apparatus which performs an image processing such ascombination of images and editing.

[0004] 2. Description of the Related Art

[0005] An alpha mask is often used when clipping out an object (subjectssuch as a person, an object appearing in a picture) from an image, andexecuting a process for combining a clipped object with another imagewith a personal computer. An alpha mask is a binary image of the samesize as an original image. For example, a region having an image valueof 0 is a background, and a region having a pixel value of zero is anobject. Only a background is replaced with another image by substitutingonly a pixel having a pixel value of 0 with a pixel of another imagereferring to an alpha mask when synthesizing the original image withanother image. In such an image synthesis, it is necessary to set analpha mask precisely. There is Photoshop of Adobe Systems Incorporatedas software for performing the image combination. There will now bedescribed an extraction tool adopted in the Photoshop version 6 (AdobePhotoshop 6.0 Japanese edition user guide, p. 154 to 157). Originalimages 1, 2, 3 and 4 shown in FIG. 4 as an example are combined togenerate a composite image A shown in FIG. 5. In this case, a pluralityof original images are arranged in a plurality of layers, respectively.The layer is for deciding the overwrite order of the original images.The composite image is generated by overwriting in turn the upper layerson the image of the lowest layer used as furring.

[0006] In other words, the original image from which an object is to beclipped and combined is selected. The pointer of a mouse is moved onthis original image to set an object region. When a preview is carriedout in a setting process, a background region is displayed by a givenpattern (in this case whole area is in white) like the object image 3-1of FIG. 6. Thus, the background region and the object region can beconfirmed. The alpha mask in this case is shown in the alpha mask 3-1.When the border of this object region is deviated from the contour of anactual object as with the object images 3-2 and 3-3 of FIG. 6, it ispossible to modify the image with a pen tool again. When the “Enter”button is pressed, an extraction dialogue becomes extinct in a resultthat the background region of the original image is erased. When thelower layer image is not disposed with respect to the original imagebeforehand, the background is displayed with being replaced with anotherpattern. However, if the lower layer image is disposed, a compositeimage is displayed.

[0007] In an example of the above-mentioned composite image A, the leftside of the original image 3 appears on the composite image, but thelower side is covered by a car in front. Therefore, the object image 3-3must be modified with respect to its object region. However, the objectimage 3-2 requires no modification of the object region, because theerror in the object image 3-2 does not appear on the composite image.However, in the case of the extraction tool of Photoshop (Trademark),the composite image cannot be confirmed till the extraction work isfinished. For this reason, even if it is the object image 3-2, themodification work cannot be omitted. As a result, a user must carry outa useless activity. As thus described, the conventional method must seta correct object region than need, resulting in increasing a workingtime.

BRIEF SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide an imageediting method and an image editing system which can edit an imagewithout setting an object region needlessly at the time of making up ofan alpha mask.

[0009] According to an aspect of the present invention, there isprovided an image editing method comprising: storing a plurality oforiginal images; storing a plurality of alpha masks corresponding to theplurality of original images, respectively, superposing in turn aplurality of object images that are extracted from the plurality oforiginal images by the plurality of alpha masks, to display a compositeimage on a first display region of a display screen; modifyingselectively the alpha masks on a second display region of the displayscreen to modify the composite image; and displaying the composite imagereflecting modification of at least one of the alpha masks on the seconddisplay region.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0010]FIG. 1 shows flowchart to explain an image editing methodaccording to an embodiment of the present invention;

[0011]FIG. 2 shows a screen of a personal computer used for executingthe image editing method according to the embodiment;

[0012]FIG. 3 shows a block diagram of an image editing apparatus tocarry out the image editing method according to the embodiment;

[0013]FIG. 4 shows an example of an original image;

[0014]FIG. 5 shows an example of a composite image;

[0015]FIG. 6 shows an example of an object image and an alpha mask;

[0016]FIG. 7 shows an example of a time sequential original image;

[0017]FIG. 8 shows an example of a composite image with the use of atime sequential original image;

[0018]FIG. 9 shows a screen of a personal computer used for an imageediting apparatus according to an embodiment of this invention;

[0019]FIG. 10 shows a screen of a personal computer used for an imageediting apparatus according to an embodiment of this invention;

[0020]FIG. 11 shows a block diagram of an image editing apparatusaccording to another embodiment of the present invention;

[0021]FIG. 12 shows a screen of a personal computer used for an imageediting apparatus according to another embodiment of the presentinvention;

[0022]FIG. 13 shows a flow chart of a process for editing an objectregion by an a plurality of workers; and

[0023]FIG. 14 shows an example which a part of a screen is painted overin black.

DETAILED DESCRIPTION OF THE INVENTION

[0024] There will now be described an embodiment of the presentinvention in conjunction with drawings. FIG. 1 shows flowchart to carryout an image editing method according to one embodiment of the presentinvention. Referring to this flowchart, there will now be described anembodiment to do setting of an object region and displaying of acomposite image at the same time.

[0025] At first, an object image and a composite image are displayed(S11). Then, using a plurality of original images and alpha masks whichare already stored, the display image specified by a user is displayedon a window 28 in a personal computer screen 26 as shown in FIG. 2 as anobject image. A composite image is displayed on the other window 27. Thealpha mask is set according to the input of a mouse pointer (S12). Then,for example, an object pen is selected from a toolbar 29 as shown inFIG. 2, and the pointer is moved in the window 28 to set an objectregion. A change of an original image in which an object region is to beset is requested from a user.

[0026] Whether the change of the original image is requested isdetermined (S13). When this determination is YES, the object image ischanged and the process is returned to step S12 (S18). When thedetermination is NO, whether the alpha mask is changed is determined(S14). When the original image is not changed, the process is returnedto step S12. When the original image is changed, the object image isupdated (S15). The composite image is updated according to the changedalpha mask (S16).

[0027] Next, it is determined whether setting of the object regionsetting and end of the composite image display are requested by the user(S17). When the determination is NO, the process is returned to stepS12. When the determination is YES, the process ends.

[0028] A block circuit of an image editing system for executing theimage editing method of the flow chart of FIG. 1 is shown in FIG. 3.According to this block circuit, a storage unit 101 is configured by aharddisk of a personal computer, a semiconductor memory, a magneticstorage medium. The storage unit 101 stores a file of a plurality oforiginal images beforehand. Assuming that the original images areoriginal images 1, 2, 3 and 4 shown in FIG. 4.

[0029] The original image data 102 read from the storage unit 101 isinput to an object image generator 103. The original image data is apart of the original images stored in the storage unit 101. The objectimage generator 103 generates an object image expressing the settingsituation of the object region of the original image. If the objectimage generator 103 is a personal computer, it is not exclusive hardwarebut may be a CPU. An alpha mask setter 109 and composite image generator111 described latter may be constructed by a CPU.

[0030] The object images include, for example, an image whose backgroundregion is painted over with a given color, an image whose backgroundregion is replaced with a given pattern. If the background region is animage colored with semi transparency, the pattern of the background canbe confirmed, and the setting situation of the alpha mask can beunderstood. Similarly, the object region may be an image colored withsemi transparency, and the background region and object region arecolored with different semitransparent.

[0031] In the initial state of the object region setting, a given alphamask, for example, a full-scale object or a full-scale background isused. The object image data 104 is sent to a memory 105, and storedtherein. Object image data 106 is sent to a display 107 at a constanttime interval or a timing for refreshing a screen from the memory 105,and displayed thereon. This display 107 assumes the screen of a personalcomputer as shown in FIG. 2. This personal computer screen 26 displays acomposite image display window 27 for displaying a composite image, anobject image display window 28 on which the object region is set and atoolbar 29 used for the object region setting. Icons representing anobject pen and a background pen are arranged on the toolbar 29. Theobject pen or background pen can be select by clicking selectively theseicons. When the display image of the window 28 is modified by the objectpen or background pen, this modification is reflected on the compositeimage displayed on the window 27 promptly. The menu used for reading andsaving an image file is prepared on the window 28.

[0032] The user confirms the setting situation of the object region andmodifies the image appropriately, while he or her watches the image onthe screen 26. For example, the user selects an object pen from thetoolbar 29, and traces a part that is an object in the original imagebut a background in the current alpha mask to change the part to theobject region. When the part is a background in the original image, butan object in the current alpha mask, the part is modified by thebackground pen. As described above, operation information 108 of theuser that regards to a movement of the pointer of a pointing device 115such as a mouth is input to an alpha mask setter 109. The alpha mask 110changed according to the operation information 108 is sent to an objectimage generator 103 to update the object image. The pointing device 115may use a touch panel or a pen tablet.

[0033] A plurality of original image data 102 used for composition, theoriginal image data of original images 1-4 shown in FIG. 4 are input tothe composite image generator 111. Each alpha mask of the original imagedata 102 of the original images 1-4 is sent to the composite imagegenerator 111 from the storage unit 101 or alpha mask setter 109. Thecomposite image generator 111 combines a plurality of original images1-4 in a given order referring to the alpha mask to generate a compositeimage A (FIG. 5).

[0034] In the example of FIGS. 4 and 5, the original image 1 is a lowerlayer image. The original images 2, 3 and 4 are overwritten on the lowerlayer image to generate a composite image A. In other words, at firstwhen the object image is extracted from the original image 1 by thecorresponding alpha mask, the data of the object image is stored in thememory 113 and sent to the display 107 therefrom. As a result, theobject image of the original image 1 is displayed on the composite imagedisplay window 27.

[0035] When the object image of the original image 2 is extracted usingthe corresponding alpha mask, the data of the object image is stored inthe memory 113. The object image of the original image 2 is displayed onthe window 27 with being superposed on the object image of the originalimage 1. In this time, when a part protruded from the object image ofthe original image 2, for example, a part of a road shown behind thevehicle body as shown in the object image 3-3 of FIG. 6 is displayedwith being superposed on the front part of the object of the originalimage 1, that is, the vehicle body, the user modifies the alpha maskcorresponding to the original image 2 in the window 28 displaying theoriginal image 2 with the object pen to delete the protruded part. Thisdeletion can be confirmed in the composite image window 27. Similarly,when the object image of the original image 3 is extracted using thecorresponding alpha mask, the data of the object image is stored in thememory 113. The object image of the original image 3 is displayed on thewindow 27 with being superposed on the composite image of the originalimages 1 and 2. Then, a part protruded from the object image of theoriginal image 3, for example, a part of a road indicated on the frontwheel of the vehicle body as shown in the object image 3-3 of FIG. 6appears on the composite image of three original images as a protrudedpart.

[0036] However, since this extrusion is a part of the road, even if theobject image of the original image 4 is not superposed on the objectimage of the original image 3, the extrusion can be incorporated in thecomposite image without sense of incongruity. If this extrusion is not apart of the road, the object image of the original image 4 is superposedonce on the object image of the original image 3 to confirm whether theextrusion is hidden by the object image of the original image 4. If theextrusion is not hidden by the object image of the original image 4, inthe window 28 displaying the original image 3, the corresponding alphamask is modified with the object pen to erase the extrusion. Thiserasure of the extrusion can be confirmed on the composite image window27. The object image of the original image 4, that is, the vehicle bodyis extracted by the corresponding alpha mask, and superposed on theprevious image while modifying the alpha mask as necessary. As a result,the composite image A shown in FIG. 5 is generated.

[0037] As discussed above, according to the present embodiment, thecomposite image indication window 27 and object image display window 28are displayed on the personal computer screen. A plurality of originalimages allocated to hierarchy layers and alpha masks corresponding tothe original images are taken in sequentially. The object region of theoriginal image is extracted using the corresponding alpha mask on theobject image display window 28. The object regions are superposed whilewatching the composite image window 27. The alpha mask is modified asnecessary to generate a suitable composite image.

[0038] When the composite image is generated as described above, thealpha mask 110 finished by modification is sent to the storage unit 101.In FIG. 3, a portion surrounded by a dotted line is called an alpha maskgenerator 116.

[0039] By the above constitution, it is possible to set the objectregion while ensuring the composite image, a part making quality of thecomposite image deteriorate is modified. As described above, when thecomposite image A of FIG. 5 is made up, in the case of the object image3-3 of FIG. 6, the car behind is overwritten by the extrusion on theleft hand side of this car, in a result that a good composite image isnot provided. For this reason, while confirming the composite image onthe composite image window 27, this extrusion is deleted on the objectimage window 28.

[0040] On the other hand, in the object image 3-2, the extrusion doesnot appear on the composite image because it is overwritten by a car ofthe original image 4. Therefore, it is found that the object image 3-2does not need to be modified. Because the modification of the alpha maskis reflected in the composite image promptly, it can be convenientlyconfirmed whether the modification is sufficient.

[0041] Updating of the composite image is repeated with a comparativelyshort time interval. When great throughput due to this repetitiveprocess wants to be avoided, the composite image is updated at a timingthat movement of a pen is stopped or the timing when the pen lefts ascreen. Alternatively, when the alpha mask is changed, the compositeimage is updated. If only a part of the composite image that is changedin the alpha mask is overwritten, the throughput of the updating can bereduced.

[0042]FIGS. 7 and 8 show original images and composite images in theembodiment of the present invention that is applied to a video image.FIG. 7 shows a scene where an interest car gradually approaches from adistant place. Such a moving image and an alpha mask of each frame arestored in the storage unit 101. The image which the user wants tofinally make is a composite image B4 of FIG. 8. In this example, theoriginal image is a video image, but the composite image is a stillimage obtained by superposing cars of original images 6, 7 and 8 on anoriginal image 5. Even in this case, if the alpha mask is modified whileconfirming the composite image, no alpha mask that is more accurate thanrequired can be formed.

[0043] There is a case that the composite image has a plurality offrames to be displayed in a video image, and object regionscorresponding to the frames are set. The composite image B1 of FIG. 8 isthe same image as the original image 5 of FIG. 7, and the compositeimage B2 is an image obtained by combining the original image 5 with acar of the original image 6. The composite image B3 is an image obtainedby combining cars of the original images 6 and 7 with the original image5. Displaying the composite images B1, B2, B3 and B4 sequentiallygenerates a moving image. In this case, the quality of the compositeimages B2 and B3 as well as the composite image B4 is important, too.Consequently, when the alpha image of the original image 7, for example,is modified, an image corresponding to the composite image B3 made upusing only the original images 5, 6 and 7 is displayed. For example,even if a part of the road of the original image 7 is combined with anobject region protruding, if the part is indistinctive in the compositeimage, it can be confirmed that the original image needs not to bemodified. On the contrary, when the car behind is overwritten by theextrusion, the modification is necessary. This situation can beunderstood from FIG. 8.

[0044] If the composite image to be displayed when the alpha mask ismodified is displayed in a form of a moving image, the throughputincreases. However, the composite image can be confirmed in a lastdisplay form. For example, even if a certain frame includes an error, itcan be determined that the frame need not be corrected if the error isdisplayed only for a moment.

[0045] If the frames of the composite image are displayed injuxtaposition on the screen, that is, four images of FIG. 8 aredisplayed in juxtaposition, all frames can be conveniently confirmed ata time. When many objects are combined as shown in the composite imagesA and B4, which object is modified cannot be determined instantly. Forthis reason, if, in the composite image, the modified object is coloredthinly, surrounded with a dotted line, or marked with a pattern such asslanted lines, the modified object can be distinct in easy.

[0046] A user selecting an image file name can change the original imageto which an object region is set in easy. Alternatively, when a point ofthe composite image is clicked, the original image that the point isincluded as an object region or the point is near the object region isautomatically displayed. In this case, if a portion that the compositequality of the composite image is no good is simply clicked, an originalimage to be modified is conveniently displayed.

[0047] When the composite image is saved in the storage unit, there is asituation that a file size should not be made too big. To do so, it isconvenient to display, on the window 27 or window 28, the file size whenthe composite image is stored in the storage unit. The user can providea contrivance for reducing the number of objects and the number offrames while watching the numeric value of the file size if the filesize is too big.

[0048] Another example of a personal computer screen is shown in FIG. 9.Thumbnail images 203 corresponding to the original images are displayedon an original image display window 202 in a screen 201. Thanks to this,the image used for composition can be confirmed easily. The compositeimage is displayed on the composite image window 204. The frame of thecomposite image can be moved backward and forward by operation of aslide bar 205 in the case of the moving image.

[0049] The user clicks the thumbnail image 206 corresponding to theimage including an object region to be modified or drags the thumbnailimage 206 on the object image window 207. As a result, an object imageis displayed on the object image window 207, to permit editing of theimage. The image is modified using a pen tool in a toolbar 208. Thethumbnail image 206 is displayed so that it is found that the image isunder edition. For example, if an original image that is colored orsurrounded by a thick frame is a video image, the display frame of theobject image can be moved backward and forward by operation of the slidebar 209. When only some frames of the original image is to be used forcombination, a start frame pointer 210 and an end pointer 211 areprepared. The pointers 210 and 211 are arranged on a start frame and anend frame of frames used for combination, respectively, to use only theframes between the start and end frames for combination. Accordingly,when the number of the composite frames is larger than that of the setframes, the original image is repeated or the last frame is stopped.Alternatively, the image is reproduced backward in time from the lastframe. When the image 206 is edited simultaneously with the image 206,the thumbnail image 212 is clicked. Then, the object image window 213 isopened and editing is enabled. Similarly, this figure shows an examplethat editing of three images is possible at the same time.

[0050] Another embodiment of a personal computer screen is shown in FIG.10. Since a composite image window 302 in a personal computer screen 301and an object image window 303 are the same as that of the previousembodiment, a detailed explanation is omitted. The thumbnails of alloriginal images stored in a hard disk are displayed on a image listwindow 304. When an image used actually for combination is clicked, thethumbnail image corresponding to the image moves to a composite listwindow 305, and simultaneously the composite image is displayed on thecomposite image window 302. Alternatively, the thumbnail image on theimage list window 304 drags to the composite list window 305 orcomposite image window 302 to move the image to the composite list.

[0051] The original image used for the composite image is displayed witha thumbnail image on the composite list window 305. When any one of thethumbnail images is clicked or the thumbnail image drags to the objectimage window 303, this alpha mask can be edited. When the thumbnailimage of the composite list window 305 is dragged to the image listwindow 304, the image is removed from the composite image.

[0052] An embodiment for setting an object region for original imagefiles located at a place using a plurality of computers will bedescribed referring to FIG. 11. According to this, the original image403 stored in the storage unit 402 of a server 401 is input to a client404 corresponding to another computer. In the client 404, an alpha mask406 is generated by each of alpha mask generators 405 shown in FIG. 11,and returned to the storage unit 402 of the server 401. Similarly, alphamasks are generated with a plurality of clients. According to thisembodiment, many operators are necessary, but many alpha masks aregenerated in a short period of time by a parallel operation.

[0053] A LAN and a public correspondence are connected between theserver and each client. Each client sends the original image in editingto the server so that a plurality of editing tasks are not executed forthe same original image at the same time. The server holds informationof the original image in editing, and each client reads the informationto prevent the original image in editing from further editing.

[0054] The screen of the client 404 shown in FIG. 11 is shown in FIG.12. The composite image is displayed on the composite image window 502in the screen 501. The server sends the data of the original image andalpha mask. The thumbnail images of the original image are displayedside by side on an original image display window 503. When the thumbnailimage 504 of the image corresponding to an alpha mask to be edited isselected and clicked, the object image is displayed on the object imagewindow 507 to make editing possible.

[0055] The process on the object image window 507 is similar to theabove embodiment. In the present embodiment, another user edits an alphamask in another client at the same time. In this case, a monitor window508 is provided for confirming the work situation of another user anddisplays the object image in editing in another client. Also, the objectimage in editing in another client is displayed on a monitor window 509.

[0056] In the original image display window 503, the thumbnail image 505in editing in another client is colored with a color different from thatof the thumbnail image 504. As a result, the original images that arenot edited can be discriminated easily. An original image to be editednext is selected from the non-edited original images. The alpha masks inediting are held in the clients, respectively, and transferred to theserver sequentially, to monitor respective editing situations to oneanother. Each client reads the alpha mask to generate the object imagefor monitoring and updating the composite image. Then, if the transferfrequency is decreased or the transfer is performed first when theoperator saves the alpha mask, the monitoring frame rate decreases, butthe quantity of transfer data can be reduced.

[0057] The process in the embodiment of FIG. 11 will be describedreferring to a flow chart of FIG. 13.

[0058] At first, the original image and alpha mask are read from theserver 401, the object image and composite image are displayed and theobject image in another client is displayed as a monitor image (S21).The alpha mask is set according to the input of the mouse pointer. Theuser changes the original image in order to set the object region. Themonitor information is updated (S22). The monitor information representsinformation indicating which original image is edited or modificationsituation of the alpha mask.

[0059] It is determined whether monitoring is updated after step S22(S23). In this determination, when the original image of an object to beedited is changed in another client, or when the alpha mask is modified,the process for updating the monitoring image is advanced to step S29.Otherwise, the process is advanced to step S24.

[0060] Whether the change of the original image is requested isdetermined in step S24. If the determination is YES, the processadvances to step S31. The determination is NO, the process advances tostep S25. In step S25, whether the alpha mask is changed is determined.When the determination is NO, the process returns to step S22. When thedetermination is YES, the process advances to step S26. In step S26, theobject image is updated according to the alpha mask changed and theprocess advances to step 27. In this step 27, the composite image isupdated according to the changed alpha mask. Thereafter, it isdetermined whether the user requests to end setting of the object regionand displaying of the composite image displaying. When the determinationis NO, the process returns to step S22. When the determination is YES,the process is ended.

[0061] In step S29, the monitoring image is updated based on themonitoring information, and the process advances to step S30. When thealpha mask is modified in another client, the composite image is updatedaccording to the modification. In step S31, the object image is changedto the image that the user requires, and the process returns to stepS22.

[0062] The embodiment for clipping an image is described hereinbefore.There is such case as to add, to some regions of an image, an imageeffect such as modification of color of the image, shade a license plateof a car with a black or blur it as shown in FIG. 14. To do so, afunction that a brightness value or a color of an original image can bemodified or a function that a modified result can be saved in anoriginal image file is convenient. When the image effect should be addedto a partial region of an image, there is a method to use the secondalpha mask for specifying the region. The alpha mask described aboveexpresses an object region that is clipped and combined with anotherobject region. The second alpha mask is decided to be used for a processfor blurring only a region whose pixel value is “1”, for example. If thesecond alpha mask is used, the data of the original image is notchanged. Thus, the image effect can be changed to ON or OFF asnecessary. Similarly to the above embodiments, a region to which animage effect is to be added is colored with semi transparency tofacilitate a distinction of the region, and the second alpha mask isedited while watching the object image window. The image to which theimage effect is really applied is displayed on the composite imagewindow.

[0063] As described above, according to the invention, since thecomposite image region can be always confirmed, it is not necessary toset a correct object region than need, resulting in decreasing a workingtime.

[0064] Additional advantages and modifications will readily occur tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details and representativeembodiments shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

What is claimed is:
 1. An image editing method comprising: storing aplurality of original images; storing a plurality of alpha maskscorresponding to the plurality of original images, respectively,superposing in turn a plurality of object images that are extracted fromthe plurality of original images by the plurality of alpha masks, todisplay a composite image on a first display region of a display screen;modifying selectively the alpha masks on at least one second displayregion of the display screen to modify the composite image; anddisplaying the composite image reflecting modification of at least oneof the alpha masks on the first display region.
 2. The image editingmethod according to claim 1, wherein the plurality of original imagesare still pictures.
 3. The image editing method according to claim 1,wherein the plurality of original images are frame pictures of a videoimage.
 4. The image editing method according to claim 3, wherein thecomposite image is a moving image, and a N-th frame of the moving imageshows a composite image of object images included in a first frame ofthe original image to the N-th frame.
 5. The image editing methodaccording to claim 3, wherein the composite image includes an imageobtained by combining object images included in a first frame to a M-thframe, and the displaying includes displaying at least two compositeimages.
 6. The image editing method according to claim 1, wherein thedisplaying includes setting a specific object image to which displayprocessing different from other processing is subjected, and thesuperposing includes switching the specific object image according tothe original image whose object region is to be set..
 7. The imageediting method according to claim 1, wherein the modifying includesmodifying the alpha mask by moving a pointer on the display screen andchanging the composite image when the pointer is stopped.
 8. The imageediting method according to claim 1, which includes determining, as anoriginal image to be processed, one of an original image including apoint to be processed in the alpha mask and an original image that apoint to be processed is near the alpha mask when a point of thecomposite image is specified, as a point to be processed, by a pointeron the display screen.
 9. The image editing method according to claim 1,wherein the modifying includes displaying the plurality of alpha maskson a plurality of second display regions, respectively, and modifyingthe alpha masks on the second display regions.
 10. The image editingmethod according to claim 1, wherein the original image includes amoving image comprising of a plurality of frames, and which includearranging a tool used for changing the frames near the alpha maskdisplayed.
 11. The image editing method according to claim 1, whereinthe composite image includes a moving image comprising of a plurality offrames, and which includes arranging a tool used for changing the framesnear the first display region displaying the composite image.
 12. Theimage editing method according to claim 1, wherein the modifyingincludes displaying thumbnail images generated by reducing the originalimages on a third display region of the screen, and displaying athumbnail image corresponding to the alpha mask being modified withbeing distinguished from the other.
 13. The image editing methodaccording to claim 1, wherein the modifying includes displayingthumbnail images generated by reducing the original images on a thirddisplay region of the screen, and determining to modify the alpha maskcorresponding to the original image corresponding to the thumbnail imagewhen the thumbnail image is clicked or when the thumbnail image isdragged to the second display region displaying the alpha mask.
 14. Theimage editing method according to claim 1, wherein the modifyingincludes displaying first thumbnail images generated by reducing theplurality of original images on a third display region of the displayscreen, displaying second thumbnail images of original images used forthe composite image on a fourth display region of the display screen,and clicking one of the second thumbnails on the fourth display regionor dragging the second thumbnail image to the third display region. 15.The image editing method according to claim 1, which includes generatingalpha mask data having different pixel values between an object regionof the alpha mask and a region aside from the object region, and whereinthe modifying includes modifying the composite image when the alpha maskdata is changed.
 16. The image editing method according to claim 1,wherein the superposing includes combining a current frame and a pastframe corresponding to the alpha masks.
 17. An image editing apparatuscomprising: a memory unit configured to stores a plurality of originalimages; a generator which generates a plurality of alpha maskscorresponding to the plurality of original images, respectively; asuperposing unit configured to superpose in turn a plurality of objectimages that are extracted from the plurality of original images by theplurality of alpha masks, to display a composite image on a firstdisplay region of a display screen; a modifying unit configured tomodify selectively the alpha masks on a second display region of thedisplay screen to modify the composite image; and a display unitconfigured to display the composite image reflecting modification of atleast one of the alpha masks on the second display region.
 18. Acomputer system for video editing, comprising: means for storing aplurality of original images; means for generating a plurality of alphamasks corresponding to the plurality of original images, respectively;means for superposing in turn a plurality of object images that areextracted from the plurality of original images by the plurality ofalpha masks, to display a composite image on a first display region of adisplay screen; means for modifying selectively the alpha masks on asecond display region of the display screen to modify the compositeimage; and means for displaying the composite image reflectingmodification of at least one of the alpha masks on the second displayregion.
 19. A video edition program stored in a computer readablemedium, comprising: means for instructing a computer to store aplurality of original images; means for instructing the computer togenerate a plurality of alpha masks corresponding to the plurality oforiginal images, respectively; means for instructing the computer tosuperpose in turn a plurality of object images that are extracted fromthe plurality of original images by the plurality of alpha masks, todisplay a composite image on a first display region of a display screen;means for instructing the computer to modify selectively the alpha maskson a second display region of the display screen to modify the compositeimage; and means for instructing the computer to display the compositeimage reflecting modification of at least one of the alpha masks on thesecond display region.